Wireshark is a must-have (and free) network protocol analyzer for any security professional or systems administrator. It's like Jaws, only for packets. Wireshark is the world’s leading network traffic ...
The Swiss army knife of free network defense tools, Network Security Toolkit (NST) takes the best-of-breed approach by bundling a whole bunch of utilities under one mantle, including Kismet, Snort, ...
Before you say anything, yes, I know Wireshark is available for Linux. This time, however, Windows and OS X users get to play too. Wireshark is an open-source network analyzation tool that is really ...